Devices which record magnetic or optical signals on magnetic or optical tape are known. Typically, these devices accept tape which is stored on an open reel or in a cassette and cause the media to be drawn past a transducer, which is fixed or moving, to allow signals to be read or written on selected regions of the tape. Because relatively long lengths of tape are used for recording significant amounts of information, the tape is typically stored on reels and the tape drawn past the transducer by a capstan or some other mechanical means. Pulling on the tape puts tension on the media which may cause it to wear, distort or even break in extreme cases such as a malfunction of the device. In addition, the inertia of the mass of tape stored on the reels results in relatively slow acceleration and deceleration of the tape packs on the reels. Rapid acceleration and deceleration also place significant stress on the tape. The amount of time required to accelerate and decelerate the tape packs limits the access time with which information can be encoded on the tape or read back from the tape by the drive system and transducer.
As the need for capturing more information in smaller spaces grows, the tape may be made thinner so that more tape surface can be stored in a given volume of storage space, such as a cartridge or cassette. Thus, tapes having a thickness of 25 .mu.m or less are common, and 13 .mu.m thick tape is often used. The fragile nature of such tape makes rapid access to random regions of the tape difficult because of the stress that is placed on the tape during rapid acceleration and deceleration of the tape packs.
U.S. Pat. No. 3,653,568 (Cronquist I) discloses a pneumatic system for moving an elongated strip of flexible tape around a loop-shaped conduit. The tape is moved through a continuous and substantially enclosed passageway or tunnel within the conduit that has dimensions slightly greater than the tape moving therethrough. The tape is transported through the tunnel by an air flow which enters the tunnel from both sides of the tape at four locations spaced around the loop. The air flow is exhausted through four pairs of apertures spaced around the loop.
The pneumatic system disclosed in Cronquist I has several disadvantages. First, because only four pairs of output nozzles are provided, the tape is not uniformly supported within the runnel. As a result of this non-uniform support, the tape will tend to contact the inner surface of the tunnel as it moves around the loop, resulting in wear or damage of the tape. The tact that the tunnel is enclosed, resulting in the need to provide exhaust openings within the tunnel, may also contribute to the non-uniform support of the tape. Second, because the air flow is directed at the tape from both sides of the tape, the air flow from above and below the tape must be symmetrical. All of the nozzles would probably have to be carefully tuned or calibrated to provide the appropriate air flow pattern within the tunnel. The nozzles might also have to be re-calibrated for different lengths of tape. Third, the duct design is fairly complex.
U.S. Pat. No. 3,705,413 (Cronquist II) discloses a data processing system for storing a large number of tape strips. The strips are provided in a closed passageway having slits at either end leading to a complex strip diverter mechanism. The strips are blown through the system in a relatively uncontrolled fashion. As a result, the strips can be expected to contact the walls of the passageways, thereby limiting the speed of the strips (thus limiting access time), and wearing or otherwise damaging the surface of the strips, thereby destroying data encoded in the strips.